x86 architecture questions

From: ziliath (ziliath_at_myway.com)
Date: 03/23/04 

Date: Tue, 23 Mar 2004 22:33:49 +0000 (UTC)

Hi all,

I've been dealving into the glory-and-gore that is the x86
architecture, and I have a few questions for the gurus...

1. Is there a way to have paging on for some tasks and
off for others? I want some fixed-size processes to enjoy
the greater speed of never paging. To put it differently,
can the paging-on flag be set and cleared at will by a kernel?

2. What compilers support 36-bit addressing? Or, if the systems
on which my kernel will run have only 32 lines wired up, can you think
of any risk in enabling 32-bit addressing anyway? (I want to
use 2-MB pages.)

3. Dumb question: can a privilege level 0 tasks (a kernel)
easily access the data of level 1/2/3 tasks ?
I am trying to figure out why Unix/Linux are supposedly
notorious for copying data instead of using pointers, if that
makes sense.

4. Which privilege levels are normally assigned to user-space tasks
on the x86? Is multithreading typically accomplished at level 3,
with apps at level 2? How does Hyperthreading complicate the picture?

5. Let's say that hypothetically, my OS will use only the 4 or 2
meg pages, never 4kB. Is there a way to ensure that the TLB
will not be invalidated with every task switch? I'm under the
impression that invalidation is automatic.

I hope these questions didn't seem too dim... I've only just
begun plowing through the Intel manuals.

Thanks,
Z

Relevant Pages

  • [GIT PULL] x86/kbuild for v2.6.31
    ... x86: add a Kconfig symbol for when relocations are needed ... boot: follow standard Kbuild style for compression suffix ... set up the decompression stack as early as possible ... defconfig: update kernel position parameters ...
    (Linux-Kernel)
  • Re: x86 architecture questions
    ... > the greater speed of never paging. ... > on which my kernel will run have only 32 lines wired up, ... The same applies to segmentation in general. ... Start with Pentium 4 class machines, ...
    (comp.lang.asm.x86)
  • Re: [PATCH -tip/master] x86: nmi_watchdog - documentation fix
    ... Subject: x86: nmi_watchdog - documentation fix ... This can be used to debug hard kernel lockups. ... In order to use the NMI watchdog, you need to have APIC support in your ...
    (Linux-Kernel)
  • Re: FatELF patches...
    ... If it's x86 vs. AMD64, then the installer can already do most of the ... good at binary compatibility with user space back as far as I can ... The kernel part refers to kernel modules. ...
    (Linux-Kernel)
  • Re: [Linux-fbdev-devel] Generic VESA framebuffer driver and Video card BOOT?
    ... >> kernel image or that the image is corrupt or that hardware diagnostics failed. ... Well being able to use this BIOS emulator logic to bring up the primary ... the same as Open Firmware really). ... Actually there is nothing wrong with the x86 BIOS from the perspective of ...
    (Linux-Kernel)